Shrinkage-control treatment for knitted fabrics

ABSTRACT

Durable-press knitted fabrics of cotton or cotton-synthetic fiber blends have been rendered essentially stable to laundering. Resistance to dimensional change in laundering has been attained by inducing shrinkage through a wet or dry agitation after treatment. Relatively little loss of fabric area occurs in the process.

United States Patent 1191 Verburg et al.

[ 51 June 24, 1975 SHRlNKAGE-CONTROL TREATMENT FOR KNITTED FABRICS [75]Inventors: Gerald B. Verburg, Metairie; John G. Frick. Jr.; John D.Reid, both of New Orleans. all of La.

[73] Assignee: The United States of America, as

represented by the Secretary of Agriculture. Washington, DC.

22 Filed: .lan.3l, 1973 211 App]. No.: 328,199

[52] US. Cl. 8/1491; 8/183; 8/185;

8/186 [51] Int. Cl. D06c 1/02 [58] Field of Search 8/183. 185. 186,149.2

[56] References Cited UNITED STATES PATENTS 3.257739 6/1966 Wentz 8/1492X 3,660.013 5/1972 Payet et a1. .1 8/1493 X 3.738.019 6/1973 Forg et ul.8/1492 X 3.739.496 6/1973 Buckley et al. 8/1493 X 3.765.580 10/1973Wilsker et al n 8/1493 X Primary E.raminerStephen J. Lechert, Jr.Attorney. Agent, or Firm-M. Howard Silverstein; Max D. Hensley ABSTRACT7 Claims, No Drawings SHRINKAGE-CONTROL TREATMENT FOR KNITTED FABRICS Anon-exclusive, irrevocable, royalty-free license in the invention hereindescribed, throughout the world for all purposes of the United StatesGovernment, with the power to grant sublicenses for such purposes, ishereby granted to the Government of the United States of America.

This invention relates to the process of producing knitted cotton orcotton and synthetic fabrics that have substantially reduced shrinkageon laundering without causing severe losses of fabric dimensions to themanufacturer.

More specifically, this invention relates to an improvement in theprocess of producing durable-press knitted fabric of cotton or cottonand synthetics, the improvement characterized by subjecting the fabricafter treatment with a finishing agent to a washing and drying procedureduring which the fabric is agitated in a slack condition for a briefperiod only in either the washing or drying, or both, or in a separateoperation after the drying, which provides the knitted fabric withsubstantially reduced shrinkage on laundering as well as smooth-dryingproperties and with relatively little loss of fabric length.

An additional benefit is that the improved process is applicable withmore than one type of durable-press fabric treatment.

Another additional benefit is that the process reduces the chance ofpotentially harmful chemicals from coming into contact with the textileuser either through di rect contact with the skin or through inhalation.

Shrinkage in knitted fabrics occurs when the strains built into theyarns by knitting and processing are gradually relieved on the agitationof washing and drying. The crosslinking of knitted cotton fixed theyarns in the strained position to a great extent. The amount ofrelaxation that occurs in repeated laundering is therefore reducedgreatly. The relaxation and resultant shrinkage is small enough so thatall but an unobjeetionable residual amount can be removed in a briefperiod of agitation in a wet or hot, dry state. This period can be madebrief enough so that it could be included in a normal textile processingwith little change of the process.

Untreated knitted fabrics of cotton or cotton and synthetics undergodimensional changes on laundering to the extent that they are no longersatisfactory for the purpose intended. A certain amount of thisdistortion can be prevented by chemical treatment, but to retain theusefulness of the fabric, the amount of chemical treatment is limiteddue to the increase in stiffness and loss of strength that occur. Inorder to achieve dimensional stability in the present state of the art,a resin treatment to control part of the shrinkage is used inconjunction with a mechanical pre-shrinkage that is usually carried outbefore curing of the resin. This has certain disadvantages, one beinglarge losses of fabric area to the manufacturer and the possibility ofintroducing wrinkles.

It is well known to those skilled in the art, that a cotton knitchemically treated without mechanical preshrinkage will changedimensionally a given amount on subsequent laundering. This change canbe used to leave a fabric that is dimensionally stable. It can bedivided by a number of processes between the manufacturer and theconsumer so that both benefit. The manufacturer profits in that theamount of fabric lost for a given degree of subsequent laundry shrinkagecontrol is less than that lost when mechanical pre-shrinkage isemployed. The consumer benefits in that he has a fabric that is trulystabilized against dimensional changes. The added benefit of havingnoxious odors and toxic chemicals removed from the garments in theprocess wash before they come into contact with the consumer can also berealized.

In general, it is not a practice to wash textiles following treatmentsto improve appearance and/or dimensional stability. This is well knownto those skilled in the art. It is considered to be especiallydetrimental to wash knit fabrics following treatments to improveappearance and/or dimensional stability. As disclosed by Bille, Thonig,and Schmidt in American Dyestuff Reporter, October, 1972, The finishshould not require an afterwash so that tension deformation can beavoided." However, afterwashing (process washing) of knit fabrics in aslack condition seems to relieve most tensions that remain in thefabrics. This is illustrated by the fact that very little shrinkageoccurs on subsequent laundering of fabrics which have been given aprocess wash.

Current practices in the art to achieve laundry stability are basedmainly on mechanical methods and exclude the use of wet or moist cureprocesses. It is an added advantage of the instant invention thatshrinkage control on laundering is achieved after the crosslinking stepwhich allows the use of such methods as the moist cure process.

In the chemical treatment, the crosslinking agent, or resin, can be oneof the polymethylolamide agents, or an agent derived from them, whichare commonly used in the finishing of woven cellulosic fabric. Theseagents are prepared inexpensively from formaldehyde and an amidocompound, and react readily with the cellulose of cotton. Typicalexamples are dimethylol ethyleneurea, dimethylol dihydroxyethyleneurea,dimethylol methyl carbamate, dimethylol ethyltriazone, and methylatedtrimethylol melamine. However, it is possible also to use other knowntypes of crosslinking agents with their appropriate catalyst. inaddition to crosslinking agent, the treatment may include other agentsto modify the fabric, such as, hand builders, softeners, wetting agents,fire-retardants, preservatives and moisture inhibitors.

An object of the instant invention is to dimensionally stabilize cottonor cotton-synthetic knitted fabrics to the effects of laundering in amanner that will benefit the manufacturer as well as the consumer.Although there may be many variables to the instant invention whichwould be covered by the process of the invention, a preferred embodimentis the treating of knitted cellulosic fabrics by ordinary pad-dry-curetechniques wherein the fabric is impregnated with an aqueous solutioncontaining about 6% of dimethylol dihydroxyethyleneurea which iscommonly used in the finishing of cellulosic fabrics, about 0.6%hydrated zinc nitrate to catalyze the crosslinking reaction, about 0.5%of a polyethylene softener, and about 0.1% of a wetting agent. Thetreating bath is applied to the knitted cotton fabric by a device suchas pad rolls that apply a controlled amount of the bath liquor anddistribute it uniformly on the fabric. The fabric is dried afterapplication of the treating bath and then heated briefly, or cured, topromote the crosslinking reaction. After curing, shrinkage is induced inthe treated fabric by washing and drying during which the fabric must beslack for at least part of one of the operations. The shrunken fabricmay then be incorporated into garments without the hazard of distortionand shrinkage of such garments during subsequent laundering.

Or simply, the instant invention consists of, in the process ofproducing durable-press knitted fabrics of cotton or cotton andpolyester, the improvement characterized by subjecting the fabric aftertreatment with the finishing agent to a washing and drying procedureduring which the fabric is agitated in a slack condition in either thewashing or drying, or both, or in an operation after drying, whichprovides the knitted fabric with substantially reduced shrinkage onsubsequent laundering as well as smooth drying properties and withrelatively little loss of fabric length.

Also, it consists of, in the process of producing durable-press knittedfabric of cotton, the improvement characterized by subjecting the fabricafter treatment with the finishing agent to a drying procedure duringwhich the fabric is agitated in a slack condition, which provides theknitted fabric with substantially reduced shrinkage on subsequentlaundering, and in which relatively little fabric length has been lost.

Also, it consists of, in the process of producing durable-press knittedfabric of cotton, the improvement characterized by subjecting the fabricafter treatment with the finishing agent to a washing and dryingprocedure in which the fabric is agitated in a slack condition for abrief period, which provides the knitted fabric with substantiallyreduced shrinkage on subsequent laundering, and in which relativelylittle fabric length has been lost.

Also, it consists of, in the process of producing durable-press knittedfabric of cotton, the improvement characterized by subjecting the fabricafter treatment with the finishing agent to a washing and dryingprocedure, in which the fabric is held to size, followed by agitation inthe slack condition with heat for a brief period, which provides theknitted fabric with substantially reduced shrinkage on subsequentlaundering and causes relatively little loss of fabric length.

EXAMPLES The following examples are provided to illustrate the practiceand results of the process of the instant invention and are not in anyway intended to limit the scope of the invention. Percentages shown inthe examples relating to concentrations have reference to percentage byweight of the total treating formulation. The various fabric sampleswere tested by the following methods: dimensional stability wasdetermined by measuring the changes in fabric dimensions from anoriginal inch by 10 inch set of markings, templated before the fabricwas subjected to the initial processing step; durablepress rating bycomparison with plastic replicas as described in AATCC Tentative TestMethod l24-l967.

EXAMPLE 1 A 50% solution of dimethylol didhydroxethyleneurea (DMDHEU)was diluted with sufficient water to give a 6% solids concentration,0.6% by weight of hydrated zinc nitrate (Zn(NO .6H O) added as catalyst,0.5% emulsified polyethylene added as a softener, and 0. l% alkyl arylethyleneoxide alcohol added as a wetting agent. This treating solutionwas padded onto a sample of 5.3 ounces per square yard cotton jerseyknitted fabric, so that the finished fabric contained 0.69% nitrogen.The wet impregnated fabric was dried for 20 minutes at 65C and thencured 3 minutes at lC while the fabric was secured in a frame tomaintain a 4% stretch in the lengthwise and widthwise directions.

The curing step was followed by a process wash in a washing machine at62C for l2 minutes with a nonionic detergent. The washed fabric wastumbled in a drum-type gas drier for 35 minutes between 6577C. Theprocess washed fabric exhibited a shrinkage of 3.4% in the lengthwisedirection and 2.2% in the widthwise direction and a durable-press ratingof 3.8.

The process wash was followed by six laundry cycles, using a home-typewashing machine and dryer. The laundered fabric exhibited a shrinkage ofonly 2.1% in the lengthwise direction and l.l% in the widthwisedirection and had a durable-press rating of4.0. The original fabric waslaundered with the treated and processwashed fabric and it exhibited ashrinkage of about 3l% in the lengthwise direction and about 8% in thewidthwise direction. The results given in this example are averagevalues from multiple experiments.

EXAMPLE 2 This treatment was identical to that in Example 1 through thecuring step, after which, the fabric was sprayed with a 2% solution of anonionic detergent in water and washed while held to size on the pinframe with hot running tap water for ID minutes, allowed to drain, driedfor 20 minutes at 65C, removed from the pin frame and tumbled for 35minutes between 6577C in a drum-type gas drier. The dried fabricexhibited an induced shrinkage of 5.5% in the lengthwise direction and3.3% in the widthwise direction.

After shrinkage was induced into the fabric, it was laundered fivetimes, as in Example 1. The laundered fabric exhibited a shrinkage ofonly 2.7% in the lengthwise direction and 0.4% in the widthwisedirection.

EXAMPLE 3 This treatment was identical to that in Example 1 through thecuring step, after which, the fabric was sprayed with a 2% solution of anonionic detergent in water and washed while on the pin frame with hotrunning tap water for 10 minutes, allowed to drain, removed from the pinframe and tumbled for 35 minutes between 65-77C in a drum-type gasdrier. The dried fabric exhibited an induced shrinkage of 5.3% in thelengthwise direction and 4.2% in the widthwise direction.

After shrinkage was induced into the fabric, it was laundered fivetimes, as in Example 1. The laundered fabric exhibited a shrinkage ofonly 2.3% in the lengthwise direction and 0.6% in the widthwisedirection.

EXAMPLE 4 This treatment was identical to that in Example I through theprocess wash, after which, the fabric was pin framed as near to theexisting dimensions as possible and dried for 20 minutes at 65C. Thedried fabric exhibited an induced shrinkage of 5.0% in the lengthwisedirection and 2.8% in widthwise direction.

After shrinkage was induced into the fabric, it was laundered fivetimes, as in Example l. The laundered fabric exhibited a shrinkage ofonly 2.8% in the lengthwise direction and 1.6% in the widthwisedirection.

EXAMPLE 5 A sample of 4.8 ounces per square yard of 50% cotton and 50%polyester jersey knitted fabric was processed in a manner identical tothat described in Example l. The process-washed fabric exhibited ashrinkage of 4.4% in the lengthwise direction and 5.8% in the widthwisedirection.

The process wash was followed by five laundry cycles each one similar tothe process wash. The laundered fabric exhibited a shrinkage of only1.7% in the lengthwise direction and 08% stretch in the widthwisedirectron.

EXAMPLE 6 The treatment was identical to that in Example 1 through thecuring step, after which, the fabric was washed in a top'loading,washing machine at 62C for 1 minute. The fabric was passed throughsqueeze rolls to remove most of the water. The remaining water wasremoved by tumbling in a home-type, gas drier for minutes between 6577C.The fabric exhibited a shrinkage of 5.8% in the lengthwise direction and3.7% in the widthwise direction.

After shrinkage was induced into the fabric, it was laundered fivetimes, as in Example 1. The laundered fabric exhibited a shrinkage ofonly 2.1% in the lengthwise direction and 1.2% in the widthwisedirection.

EXAMPLE 7 This treatment was identical to that in Example 1 through thecuring step, after which, the fabric was tumbled in a drum-type gasdrier for 35 minutes between 6577C. The tumbled fabric exhibited aninduced shrinkage of 4.9% in the lengthwise direction and 2.6% in thewidthwise direction.

After shrinkage was induced into the fabric, it was laundered fivetimes, as in Example 1. The laundered fabric exhibited a shrinkage ofonly 2.5% in the lengthwise direction and 0.8% in the widthwisedirection.

EXAMPLE 8 This treatment was identical to that in Example 1 through thecuring step, after which, the fabric was tumbled in a drum-type gasdrier for 5 minutes between 6577C. The tumbled fabric exhibited aninduced shrinkage of4.3% in the lengthwise direction and 2.6% in thewidthwise direction.

After shrinkage was introduced into the fabric, it was laundered fivetimes, as in Example 1. The laundered fabric exhibited a shrinkage ofonly 3.3% in the lengthwise direction and 1.8% in the widthwisedirection.

EXAMPLE 9 This treatment was identical to that in Example 1 through thecuring step, after which, the fabric was washed in a washing machine at62C briefly for 1 minute. The fabric was passed through squeeze rolls toremove most ofthe water. The remaining water was removed by drying in aslack condition in an oven without tumbling for 5 minutes at l 15C. Thefabric exhibited a shrinkage 0f4. 1% in the lengthwise direction and2.2% in the widthwise direction.

After shrinkage was induced into the fabric, it was laundered fivetimes, as in Example 1. The laundered fabric exhibited a shrinkage ofonly 3.5% in the lengthwise direction and 1.8% in the widthwisedirection.

EXAMPLE 10 The treatment was identical to that in Example 1 through thecuring step, after which, the fabric was sprayed with a 2% solution of anonionic detergent in water and washed while on the pin frame with hotrunning tap water for 10 minutes, allowed to drain, and dried for 20minutes at C while on the pin frame. The fabric was tumbled in a slackcondition for 3 minutes between 65-77C in a drum-type gas drier. Thedried fabric exhibited an induced shrinkage of 4.7% in the lengthwisedirection and 2.4% in the widthwise direction.

After shrinkage was induced into the fabric, it was laundered fivetimes, as in Example 1. The laundered fabric exhibited a shrinkage ofonly 3.5% in the lengthwise direction and 1.2% in the widthwisedirection.

EXAMPLE 1 l A 50% solution of dimethylol dihydroxyethyleneurea (DMDHEU)was diluted with sufficient water to give a 6% solids concentration and0.33% hydrogen chloride (HCl) added as a catalyst. This treatingsolution was padded onto a sample of 5.3 ounces per square yard cottonjersey knitted fabric, so that the finished fabric contained about 0.65%nitrogen. The wet impregnated fabric was secured in a frame to produce a4% stretch in the lengthwise and widthwise directions. The fabric wasdried with a forced air flow at ambient temperatures to about 9%moisture and placed in a sealed plastic bag for curing at about 23C forabout 20 hours during which the stretch was maintained.

The curing step was followed by a process wash in a washing machine at62C for 12 minutes with a nonionic detergent. The washed fabric wastumbled in a drum-type gas drier for 35 minutes between 6577C. Theprocess-washed fabric exhibited a shrinkage of 8.3% in the lengthwisedirection and 4.7% in the widthwise direction and a durablepress ratingof 3.4.

The process wash was followed by six laundry cycles using a home-typewashing machine and drier. The laundered fabric exhibited a shrinkage ofonly 2.2% in the lengthwise direction and 1.1% in the widthwisedirection and a durable-press rating of 3.3. The results given in thisexample are average values from multiple experiments.

We claim:

1. In the process of producing finished, durable pressed, knitted,cotton-containing garments wherein cotton-containing knit fabric iscrosslinked to impart durable-press characteristics to the fabric andthen formed into garments, the improvement comprising agitating thefabric in a slack condition after said fabric is crosslinked but beforeit is formed into a garment.

2. The process of claim 1 wherein the fabric is agitated while beingwashed.

3. The process of claim 1 wherein the fabric is agitated in hot air.

4. The process of claim 1 wherein the fabric is agitated while beingwashed and dried.

5. 1n the process of producing durable-press knitted cotton-containingfabric. the improvement comprising subjecting the fabric after treatmentwith a finishing agent to drying during which the fabric is agitated ina slack condition, which provides the knitted fabric with substantiallyreduced shrinkage on subsequent launder- 7. In the process of producingdurable-press knitted cotton-containing fabric, the improvementcomprising subjecting the fabric after treatment with a finishing agentto washing and drying in which the fabric is held to size, followed byagitation in the slack condition with heat for a brief period, whichprovides the knitted fabric with substantially reduced shrinkage onsubsequent laundering and causes relatively little loss of fabriclength.

1. IN THE PROCESS FO PRODUCING FINISHED, DURABLE-PRESSED, KNITTED,COTTON-CONTAINING GARMENTS WHEREIN COTTON-CONTAINING KNIT FABRIC ISCROSSLINKED TO IMPART DURABLE-PRESS CHARACTERISTICS TO THE FABRIC ANDTHEN FORMED INTO GARMENTS, THE IMPROVEMENT COMPRISING AGITATING THEFABRIC IN A SLACK CONDITION AFTER SAID FABRIC IS CROSSLINKED BUT BEFOREIT IS FORMED INT A GARMENT.
 2. The process of claim 1 wherein the fabricis agitated while being washed.
 3. The process of claim 1 wherein thefabric is agitated in hot air.
 4. The process of claim 1 wherein thefabric is agitated while being washed and dried.
 5. In the process ofproducing durable-press knitted cotton-containing fabric, theimprovement comprising subjecting the fabric after treatment with afinishing agent to drying during which the fabric is agitated in a slackcondition, which provides the knitted fabric with substantially reducedshrinkage on subsequent laundering, and in which relatively littlefabric length has been lost.
 6. In the process of producingdurable-press knitted cotton-containing fabric, the improvementcomprising subjecting the fabric after treatment with a finishing agentto washing and drying in which the fabric is agitated in a slackcondition for a brief period, which provides the knitted fabric withsubstantially reduced shrinkage on subsequent laundering, and in whichrelatively little fabric length has been lost.
 7. In the process ofproducing durable-press knitted cotton-containing fabric, theimprovement comprising subjecting the fabric after treatment with afinishing agent to washing and drying in which the fabric is held tosize, followed by agitation in the slack condition with heat for a briefperiod, which provides the knitted fabric with substantially reducedshrinkage on subsequent laundering and causes relatively little loss offabric length.